Cohort participation and retention
Timeline of surveys since 1996
| Cohort | 1989-95 | 1973-78 | 1946-51 | 1921-26 | |
|---|---|---|---|---|---|
| Survey 1 | Year (age range) | 2013 (18-23) | 1996 (18-23) | 1996 (45-50) | 1996 (70-75) |
| Respondents (N) | 17010 | 14247 | 13714 | 12432 | |
| Survey 2 | Year (age range) | 2014 (19-24) | 2000 (22-27) | 1998 (47-52) | 1999 (73-78) |
| Respondents (N) | 11344 | 9688 | 12338 | 10434 | |
| Survey 3 | Year (age range) | 2015 (20-25) | 2003 (25-30) | 2001 (50-55) | 2002 (76-81) |
| Respondents (N) | 8961 | 9081 | 11226 | 8646 | |
| Survey 4 | Year (age range) | 2016 (21-26) | 2006 (28-33) | 2004 (53-58) | 2005 (79-84) |
| Respondents (N) | 9007 | 9145 | 10905 | 7158 | |
| Survey 5 | Year (age range) | 2017 (22-27) | 2009 (31-36) | 2007 (56-61) | 2008 (82-87) |
| Respondents (N) | 8495 | 8199 | 10638 | 5560 | |
| Survey 6 | Year (age range) | 2019 (24-29) | 2012 (34-39) | 2010 (59-64) | 2011 (85-90) |
| Respondents (N) | 8346 | 8009 | 10011 | 4055 | |
| Survey 7 | Year (age range) | 2023 (28-33) | 2015 (37-42) | 2013 (62-67) | Surveyed at six monthly intervals from November 2011 (see next table) |
| Respondents (N) | in progress | 7186 | 9151 | ||
| Survey 8 | Year (age range) | 2018 (40-45) | 2016 (65-70) | ||
| Respondents (N) | 7121 | 8622 | |||
| Survey 9 | Year (age range) | 2021 (43-49*) | 2019 (68-73) | ||
| Respondents (N) | 6875 | 7956 | |||
| Survey 10 | Year (age range) | 2022 (71-77) | |||
| Respondents (N) | 7159 |
Data known as at 7th May 2024.
*This is more than the usual 5 year age range because the survey was open for 17 months due to COVID-19.
1921-26 Cohort: number of respondents for each six-monthly follow up (6MF)
| Survey | Total (N) | Year submitted: | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Age range (years): | 85-90 | 86-91 | 87-92 | 88-93 | 89-94 | 90-95 | 91-96 | 92-98 | 93-99 | 94-100 | 95-101 | 96-102 | 97-103 | ||
| 6MF1 | 3855 | 2829 | 945 | 59 | 13 | 2 | 4 | 1 | 2 | 0 | 0 | 0 | 0 | 0 | |
| 6MF2 | 3395 | 3069 | 248 | 45 | 14 | 8 | 1 | 5 | 3 | 1 | 1 | 0 | 0 | ||
| 6MF3 | 2993 | 1651 | 1178 | 96 | 33 | 16 | 8 | 6 | 4 | 1 | 0 | 0 | 0 | ||
| 6MF4 | 2623 | 2216 | 292 | 57 | 27 | 8 | 12 | 5 | 4 | 2 | 0 | 0 | |||
| 6MF5 | 2311 | 921 | 1169 | 133 | 41 | 16 | 13 | 7 | 7 | 3 | 1 | 0 | |||
| 6MF6 | 2032 | 1591 | 299 | 64 | 33 | 18 | 11 | 8 | 5 | 3 | 0 | ||||
| 6MF7 | 1780 | 595 | 985 | 110 | 35 | 29 | 8 | 9 | 6 | 3 | 0 | ||||
| 6MF8 | 1556 | 1129 | 311 | 52 | 28 | 17 | 9 | 7 | 3 | 0 | |||||
| 6MF9 | 1376 | 439 | 737 | 133 | 33 | 14 | 9 | 6 | 5 | 0 | |||||
| 6MF10 | 1215 | 823 | 285 | 55 | 23 | 17 | 7 | 5 | 0 | ||||||
| 6MF11 | 1064 | 260 | 612 | 124 | 44 | 15 | 5 | 2 | 2 | ||||||
| 6MF12 | 911 | 569 | 252 | 54 | 22 | 8 | 6 | 0 | |||||||
| 6MF13 | 778 | 160 | 477 | 96 | 23 | 19 | 3 | 0 | |||||||
| 6MF14 | 673 | 413 | 194 | 38 | 17 | 10 | 1 | ||||||||
| 6MF15 | 555 | 116 | 329 | 71 | 24 | 13 | 2 | ||||||||
| 6MF16 | 461 | 274 | 139 | 34 | 12 | 2 | |||||||||
| 6MF17 | 374 | 79 | 224 | 51 | 15 | 5 | |||||||||
| 6MF18 | 304 | 170 | 103 | 27 | 4 | ||||||||||
| 6MF19 | 242 | 43 | 155 | 43 | 1 | ||||||||||
| 6MF20 | 192 | 110 | 69 | 13 | |||||||||||
| 6MF21 | 137 | 26 | 91 | 20 | |||||||||||
| 6MF22 | 85 | 56 | 29 | ||||||||||||
| 6MF23 | 30 | 8 | 22 |